Practices examined heretofore in the cigarette industry for perforation have included mechanical puncture, electrical are striking and laser beam treatment. These practices typically have involved perforating a web of filter tipping paper with smoke dilution thereby being effected in the cigarette filter, upon wrapping the perforated tipping paper on filter plugs.
For operation on the assembled filter cigarette, i.e., where perforations are to be made in the tipping paper after wrapping thereof upon the plug and following joinder of the tobacco cylinder and plug, the laser approach is more expeditious than the other foregoing practices. One known system for this purpose continuously rotates an otherwise complete cigarette in relation to a pulsed point-focused laser beam. On each pulse, a single hole is made in the cigarette filter. After completion of rotation, the cigarette bears a plurality of circumferentially spaced holes at a common location axially on the cylindrical plug. Since cigarettes are made back-to-back in such known system and then mutually severed midway of the dual filter plug, the laser beam is split into two beams which are incident on mutually spaced axial locations on the dual plug.
Such known laser approach has advantage in not requiring perforation of tipping paper as a practice preparatory to cigarette making and further in providing possible selection of dilution characteristics optionally at the cigarette maker on otherwise complete cigarettes by adjustment of laser apparatus operation, as contrasted with need for preselection of properly perforated tipping paper for each diverse-dilution cigarette. On the other hand, such known laser-perforation system requires that each cigarette to be perforated be subjected to a full revolution about its longitudinal axis while such axis is in spatially fixed disposition. In the known system, this relatively complex task is practiced by capturing each cigarette separately between first and second drums in a recess extending about the first drum surface and rotating the drums at identical lineal surface speed.
In effect, this known system functions, for each perforation made, in related manner to the several laser sheet material perforating systems shown in the reference discussed in the prior art statement filed herein pursuant to 37 CFR 1.97 and 1.98.